1. What is PPFD?

Photosynthetic Photon Flux Density (PPFD) measures the amount of photosynthetically active radiation (PAR) that reaches a plant's surface. It's crucial for determining if plants receive adequate light for growth.

2. How Does the Calculator Work?

The calculator uses the PPFD equation:

Where:

• \( Light\ Intensity \) — Light output at source (µmol/m²/s)
• \( Distance\ Factor \) — Diminishing factor based on distance from light source (dimensionless)

Explanation: The equation accounts for the inverse square law of light intensity over distance from the source.

3. Importance of PPFD Calculation

Details: Accurate PPFD measurement helps optimize plant growth, prevent light burn, and ensure energy efficiency in indoor growing setups.

4. Using the Calculator

Tips: Enter light intensity in µmol/m²/s and distance factor (typically between 0-1). All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What's a good PPFD range for plants?
A: Most plants thrive between 200-400 µmol/m²/s for 12-16 hours daily. High-light plants may need 400-600 µmol/m²/s.

Q2: How do I measure light intensity?
A: Use a quantum PAR meter to measure light intensity at the light source before applying distance factors.

Q3: How does distance affect PPFD?
A: Light intensity decreases with the square of the distance from the source (inverse square law).

Q4: What's the difference between PPFD and lux?
A: PPFD measures photosynthetically active photons, while lux measures visible light brightness to human eyes.

Q5: Should PPFD be constant across the canopy?
A: Ideally yes, but some variation is normal. Aim for no more than ±20% variation across the canopy.